1. Field of the Invention
This invention relates to a process for stimulating and upgrading the oil production from a heavy oil reservoir, and more particularly, but not by way of limitation, to an on-site process for stimulating oil production from a heavy oil reservoir and upgrading the heavy oil produced to more valuable readily transportable products.
2. Description of the Prior Art
A prior art process known as the hydrogen donor diluent cracking process (HDDC) is described in detail in U.S. Pat. No. 2,953,513. In accordance with the process, low value hydrocarbon fractions are upgraded by thermal cracking in the presence of a hydrogen donor diluent. An improved hydrogen donor diluent cracking process is described in detail in U.S. Pat. No. 4,115,246. In accordance with such process, the pitch fraction resulting from fractionation of the products from the hydrogen donor diluent cracking step is subjected to partial oxidation, and the hydrogen-containing gas produced by the partial oxidation step is utilized to hydrogenate the recycled hydrogen donor diluent.
Throughout the world there are a number of heavy oil reservoirs, i.e., formations containing heavy oil which cannot be recovered by conventional means due to the extremely high viscosity of the oil. Examples of such reservoirs are the tar sands or bitumen sand deposits, the larger of which are found in Canada, Venezuela and the United States. These and other heavy oil reservoirs are being produced, at least to some extent, through the use of thermal recovery processes including processes which involve the injection of steam and hot water into the reservoir to enhance the mobility of the heavy oil contained therein. While the various thermal recovery processes which have been developed and used heretofore for stimulating oil production from heavy oil reservoirs have achieved varying degrees of success, a problem common to all such processes is that once the heavy oil is produced, it is difficult to handle and particularly difficult to transport from the production site due to its high viscosity and low pour point.
By the present invention an improved process for producing heavy oil reservoirs is provided wherein the heavy oil recovered is upgraded to more valuable readily transportable products at the production site and the effluent streams from the process are either injected into the reservoir or used as fuel thereby making the process largely self-sustaining.